Plastic mold base



June 13, 1950 w. KOSOBUD PLASTIC MOLD BASE Filed Jan. 2, 1948 IN VEN TOR. mu IA M KOSOBUD.

ATTORNEY Patented June 13, 1950 UNITED STATES PATENT OFFICE PLASTIC MOLD BASE Application January 2, 1948, Serial No. 203

2 Claims.

This invention relates to mold bases for injection plastic molding, and more particularly to the ejector and ejector pin construction which forms a part of such mold base.

Heretofore the ejector pins were threaded at one end and threadably secured within the ejector plate.

Heretofore ejector pins have been formed with an annular flange at one end to be secured to the ejector plate within a corresponding undercut recess formed in a secondary ejector plate, which was secured to said first ejector plate.

It is the principal object of this invention to provide a novel means of attachment of the ejector pin to the mold ejector plate wherein said threads are eliminated as well as said annular flange.

It is the object of this invention to provide a plain cylindrically shaped ejector pin with an arcuate recess formed adjacent one end thereof. Said pin is slidably positioned within and through a secondary ejector plate which is secured to the principal ejector plate, and a locking element is positioned within said. secondary ejector plate cooperable with the main ejector plate and snugly projecting into the recess in said ejector pin for immovably securing same relative to said ejector plates.

I These and other objects will be seen from the following specification and claims in conjunction with the appended drawing in which:

Figure 1 is a partially broken awa and sectioned elevational view of the mold base.

Figure 2 is a plan view enlarged and taken on line 22 of Figure 1.

Figure 3 is an enlarged plan View taken on line 33 Fig. 1.

Figure 4 is a section on line l4 of Figure 2; and

Figure 5 is a similar View showing a portion of the secondary ejector plate with its ejector pin opening and the undercut recess for receiving the pin locking means.

It will be understood that the above drawing illustrates merely one preferable embodiment of the invention and that other embodiments are contemplated within the scope of the claims hereafter set out.

Referring to the drawing Figure 1 shows the mold base as having a substantially rectangular anchor plate II with two parallels l2 and I3 disposed thereon and secured thereto in spaced relation. Said parallels are placed inwardly of the edges of anchor plate I l to provide extending portions l4 and I5 to permit clamping thereof to a molding machine.

A back-up plate It rectangular in shape is positioned upon the top edges of parallels l2 and I3, is suitably secured thereto, and provides a means for supporting the removable and interchangeable rear cavity retainer plate H.

A corresponding front cavity retainer plate I8 is provided similar in shape to said rear cavity plate for compressive cooperative engagement with respect thereto. Both the upper surface I9 of plate I! and the lower surface 20 of plate 18 are initially blank, but are adapted to have inserted therein corresponding and mating molds and cores within which is injected a plastic material to be molded therein.

Another plate 2| corresponding to anchor plate I l is suitably secured to cavity plate I8 and similarly the edges 22 and 23 of plate 2| extend beyond the outer edges of plate I8 to permit clamping thereof within the stationary portion of a molding machine.

A rectangula ejector plate is indicated at 24 longitudinally disposed between the two parallels l2 and I3 and adapted for manually or mechanically actuated upward and downward sliding movements between anchor plate I l, and back-up plate [6 upon which cavity retainer plate I! is mounted.

A secondary ejector plate 25 is secured upon ejector plate 24 by the socket headed screws 26, and is adapted to retain and secure in upright position the spaced push-back pins 21, one of which is shown in the drawing for illustration.

An ejector pin 28 is shown in Figure l as also secured by secondary ejector plate 25 to ejector plate 24, so as to extend upwardly through corresponding openings in back-up plate l6 and also into openings within the core 29. The latter is positioned by the mold maker within rear cavity plate I! in corresponding and cooperating aligned relation with the mold 36 positioned and secured within front cavity plate 18.

Upon outward movement of ejector plate 24 25 in addition to outward movement of ejector pins 28, one of which is shown, a corresponding outward movement is given to push-back pins 21. When the cavity plates I1 and [8 are again brought together within a suitable molding ma. chine the outer ends of push-back pins 21 engage the surface 20 of plate It; whereby said ejector plate 24-25 is forced. back to its inoperative position as shown in Figure 1.

In operation, in carrying out injection molding the two plates I1 and i8 are tightly brought together and a plastic molding material is supplied through the hollow throated sprue bushing 3| for injection into the core and cavity 29 and 30.

A plurality of transverse openings 32, Figure 5, one of which is shown, are formed within secondary ejector plate 25 to slidably receive ejector pin 28, whose end is adapted to bear against the top surface of ejector plate 24.

An undercut circular recess 33 is formed in the under surface of secondary ejector plate 25, and is adapted to snugly receive the ball shaped pin locking element 34 as illustrated in Figure 4.

A concave transverse recess 35 is formed adjacent the lower end of ejector pin 28 for registry with the undercut recess 33 which is positioned relative to opening 32 in overlapping relation, as viewed in Figure 5.

The ball shaped locking element is snugly nested 1 within recess 33, and a portion thereof cooperatively projects within the arcuate recess 35 formed in said ejector pin.

In the construction shown in Figure 4 recess 33 is of sufiicient depth that the outer portion of locking element 35 is fiush with and cooperatively bears against the top surface of the ejector plate 24.

"When'the latter plate'is secured to secondary .ejector plate 25 it will be seen that ball shaped locking element 34 is immovably secured within recess 33 and also that ejector pin 28 is retainingly positioned within ejector plate 25.

By this construction relative movements between ejector pin 28 and the ejector plates 24-25 is prevented'when the same are properly secured together by means of the screws 2%.

Operation In usethe plates 24 and 25 are separated and the ejector pin-28 slidably positioned through secondary ejector plate 25 with its lower recessed 'pcrtion'extending below the surface thereof. The ball shaped locking element is manually positioned within the arcuate recess 35 in said ejector pin, and then the pin as well as the locking element 34 are-manually projected into secondary ejector'plate 25 until the lower end of said pin isflush withthe lower surface of said secondary ejector plate. At the same time the outer portion of locking element 35 is flush with said lower surface. The ejector plate 25 is then brought into cooperative bearing relation with plate 25 and .tightly secured thereto by the socket headed screws 26.

So assembled it-is clearthat ejector pin 22 is immovablysecured relative to said ejector plates.

To removethe ejector pin, it is not necessary to completelydisassemble the mold base, but on the other'hand'plates 24 and 25 are loosened sufficiently whereby the locking element 35 may be forced outof its supporting recess 33. Thisis normally accomplished merely by tapping the outer end of the ejector pin until the same slides inwardly sufficiently to permit the release of locking element 34, which will drop out. The ejector pin may then be manually withdrawn by sliding the same outwardly through secondary ejector plate 25.

The advantage of the present construction over other types resides in the fact that said ejector pin .28 may be constructed in one piece and prophardened ejector pin shank.

erly case hardened. On the other hand where the threaded type of ejector pin was previously employed, a threaded element of relatively flexible steel was welded to a heat treated case hardened shank element to produce the ejector pin. As all machining is eliminated with the exception of the formation of the arcuate recess 35, it-becomes clear that the, present construction is a substantial simplification not only in the construction of the ejector pin, but in its method of mounting.

The same thing was true in the case of the ejector'pin having an annular flange of enlarged diameteninasmuch as said flanged portion was usually machined and separately welded to a case It is clear that the present construction is a decided improvement over present andexisting ejector pin constructions and methods of mounting of ejector pins relative to the ejector plates.

Having described my invention, reference should now be'had'to the claimswhichfollowfor determining the scope thereof.

I claim:

1. The combination, an ejector plate, a "secondary ejector plate secured thereto andhaving a transverse opening therethrough, there also being a circular slot in the underside'thereof"over lapping said opening, an ejector pin slid-ably positioned through said opening andbea'ring upon said first-ejector plate, there being 'an arcuate recess formed'in said 'pin in registry with said slot, and aball shaped locking element within said slot bearing upon said first ejector plate and extending snugly into said "recess for cooperative retainingengagement with said ejector pin, said first ejector plate supporting and-securingsaid locking element within said secondary ejector plate.

2. The combination. a pair of plates secured to eachcther, one thereof having a transverse opening anda circular recess formed-in its common REFERENCES CIT-ED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,621,811 Richard-et a1. .Mar. 22, 1927 1,785,495 Richard 'De'c. 16,1930 2,330,369 Marsh Sept-28, 1943 2,339,792 Milano 'Jan. 25, 1944 2,393,986 Gullberg Feb. 5, 1946 2,419,089 Quarnstrom is--- Apr. 15, 1947 

